A cipher refers to a set of methods and algorithms used to convert information into a form that is unreadable or incomprehensible to unauthorized individuals. The main goal of encryption is to protect information from unauthorized access and ensure data security. In fact, a cipher is used in the encryption process. The aim of encryption is to create protocols or schemes that allow users to communicate securely while maintaining privacy, even in insecure environments.

Private information before encryption is referred to as plain text or clear text, and after using the cipher algorithm, it is transformed into incomprehensible information, known as cipher text. The cipher protocol is used in many network protocols, including VPNs, to keep user information confidential.

• Encryption is divided into two main categories:

1. Symmetric Encryption: One of the common encryption algorithms is symmetric encryption, which uses a single key for both encrypting and decrypting data. This means that the sender and receiver must agree on a shared key before exchanging information. Examples of symmetric encryption algorithms include AES and DES. This algorithm is one of the oldest and most well-known encryption methods still in use today.

2. Asymmetric Encryption: Asymmetric encryption, or public key encryption, is considered a more advanced version of symmetric encryption. In this type, two different keys are used: a public key that can be shared with others and a private key that is only held by the owner. This method provides greater security. RSA is one of the most well-known asymmetric encryption algorithms.

In general, the primary difference between symmetric and asymmetric encryption lies in the use of encryption keys. In symmetric encryption algorithms, one key is used for both encryption and decryption, while in asymmetric algorithms, there are two keys: one for encrypting the data and another for decrypting it.

• Advantages and Disadvantages

Both symmetric and asymmetric encryption have their own specific advantages and disadvantages. Below are the details:

Advantages of Symmetric Encryption:

1. High Speed: Symmetric encryption is usually faster than asymmetric encryption because its algorithms are simpler.

2. Efficiency: For large volumes of data, symmetric encryption is more suitable due to its higher speed and efficiency.

3. Easy Implementation: Implementing symmetric algorithms is generally easier.

Disadvantages of Symmetric Encryption:

1. Key Management: There is a need for secure key exchange between the sender and receiver. If the key is compromised, the security of the data is also at risk.

2. Scalability Limitations: In large systems with many users, managing keys becomes complex.

3. Lack of Authentication: This type of encryption cannot easily verify the identity of the sender.

Advantages of Asymmetric Encryption:

1. Easy Key Management: There is no need for key exchange; it is sufficient to share the public key.

2. Authentication: It allows for verifying the identity of the sender through digital signatures.

3. Higher Security: Even if the public key falls into unauthorized hands, without access to the private key, they cannot decrypt the data.

Disadvantages of Asymmetric Encryption:

1. Low Speed: It is generally slower than symmetric encryption, especially for large volumes of data.

2. Complexity: Asymmetric algorithms are more complex and may require more resources.

3. Large Data Volumes: For encrypting large volumes of data, symmetric encryption is often used alongside asymmetric encryption (for example, in TLS protocols).